Is there a difference between Mustang and T-bird pedal assemblies, especially regarding the brake pedal actuating rod? Maybe differences between the relative positioning of the firewall and brake MC/pedal?
Not that I have seen. I have used Mustang pedal assys in all my manual conversions with no issues.
I've got issues with my brakes, and am using the MM manual conversion kit. Are you using the factory pieces?
On my '87 TC the Mustang assembly bolted up no problems but I did have to swap the actual brake pedal.....I had to swap the TC pedal onto the Mustang assembly. The pivot point was different on the Mustang pedal and as such it was too close to the floor. Something I believe is exclusive to the ABS setup....I'm pretty sure there's no such difference on the non ABS T-Birds/Cougars.
I just installed the 5-speed pedals into my car, and remembering this thread I measured the pivot-point-to-pushrod distance. I forget the actual number, but the distance was the same between the T-Bird's automatic pedals and the Mustang 5-speed pedals.